The trend, particularly in plumbing today, is to shift from thermoplastic materials to thermoset polymers, e.g., crosslinked polyethylene wherein at least a portion of the polymer is crosslinked, for example approximately 65% thermoset/35% thermoplastic. However, this shift in materials has a significant impact on processing operations impacting these materials and there are several processing changes which must be incorporated in order to fabricate acceptable parts. The Prior Art teaches that thermoplastic material can chemically bond to itself. However, as the percentage of crosslinking increases, there is less thermoplastic remaining to form this chemical bond. In the Prior Art, as illustrated for example by U.S. Pat. Nos. 5,895,695 and 6,287,501, the conventional wisdom was believed to be the recognition of the need to form the overmolded section at the earliest time when the base underlying polymeric profile was the least crosslinked. When crosslinking using radiation, this is before any crosslinking occurs. With silane crosslinking, this is typically after extrusion, but before crosslinking is complete.
However, there are applications where the tube or other profile is more than 65% crosslinked and an injection overmolding operation is desired. To date, there is no teaching in the art as to how this may be accomplished for PEX B or PEX C. By using the technology described in this application, it is now possible to injection overmold onto profiles having a degree of crosslinking of at least 65% or greater using either silane or radiation as the crosslinking methodology, and still result in an affixation of the injection overmolded polymer (which may become crosslinked or more fully crosslinked) onto the crosslinked underlying profile which had been previously crosslinked to 65% or greater.